Many devices have been developed over the years to enable the operator of a motor vehicle to set and maintain a desired cruising (road or vehicle) speed. Some of the devices have involved fluid or electro-mechanical mechanisms connected to the engine to sense engine speed and to modify the engine throttle setting to maintain the speed at a level desired by the operator. Other devices have been utilized to directly control throttle setting rather than a predetermined engine speed. By way of example, a device that proports to sense and maintain engine speed is disclosed in U.S. Pat. No. 3,476,204, the disclosure of which is incorporated herein by reference. An example of a device that proports to maintain a desired throttle setting is disclosed in U.S. Pat. No. 3,204,734, the disclosure of which is incorporated herein by reference.
Devices have also been utilized in the past that regulate the accelerator position by balancing a potentiometer to the voltage derived from the engine ignition system at the particular engine speed occuring at the vehicle speed desired. The complexity in adjusting such devices is proportedly diminished by the cruise control system disclosed in U.S. Pat. No. 4,132,284, the disclosure of which is incorporated herein by reference, by employment of an electronic control system that drives an electrical system having a voltage that is proportional to the instantaneous speed and independent of the amplitude of the engine ignition impulses. The system, however, employs a complex mechanical arrangement that requires the pivotal mounting of an electrical motor that is rotated in opposite directions by a solenoid to engage and disengage a gear that is connected to the acceleration pedal by a flexible cable.
Although all of the previously described devices in one form or another use engine speed or an accelerator position by seek and maintain a desired pre-set vehicle speed by the operator, they have been complicated and costly to manufacture and to install and have been unable to regulate both vehicle speed and engine idling speed.
The problem of maintaining a desired engine idling speed is often as desirable as maintaining an operator selected vehicle cruising speed in order to insure optimum engine operating conditions as well as minimizing fuel consumption and smoothness of performance. Engine idle speed control systems commonly derive their control from a variety of sensed engine conditions such as desired accelerator position, desired engine rpm, engine temperature, coolant temperature and atmospheric conditions. An example of an idle speed control system that is able to integrate engine speed with a variety of additional sensed engine conditions to control engine idling speed is disclosed in my U.S. Pat. No. 4,412,518 which is assigned to the assignee of the present invention and, the disclosure of which, is incorporated herein by reference. Understandably, use of separate mechanisms to control cruising speed and engine idling speed is expensive and costly and compounds installation and maintenance costs and expenses.
In view of the above, a need exists to provide a system that not only is able to regulate vehicle speed in a simple and economical manner but is also able to regulate engine idling speed without the cost and expense of having to install separate systems for both which has heretofore been the practice in the past.